The disclosure of the following priority applications are incorporated herein by references: Japanese Patent Applications No. 10-352671 filed Dec. 11, 1998 and No. 11-217247 filed Jul. 30, 1999.
1. Field of the Invention
The present invention relates to blur correction apparatus for correcting blur in optical equipment such as a camera, detachable lens, video camera, or binoculars, etc. by moving part or all of a lens.
2. Description of the Related Art
In recent years, in order to prevent blurring in cameras, technology has become established for correcting image blurring on a film surface by detecting camera shake or camera vibration and moving a blur correction lens according to this shake.
Blur correction lens driving usually commences in synchronism with a prepare for photographing operation (an operation of half-pressing the release button, hereinafter simply referred to as a xe2x80x9chalf pressxe2x80x9d) signal of the camera and ends in synchronism with a half-press timer OFF signal. A blur correction switch is also provided on the outside of the lens barrel in order to decide whether or not to carry out blur correction control. A photographer then usually uses this switch to select whether or not the blur correction control is to be operational.
On the other hand, when the blur correction lens is not being driven, it is necessary to lock the blur correction lens at a position where the optical axis of the blur correction lens coincides with the center of the optical axis of the photographing optical system. If the blur correction lens is not locked when photographing without carrying out blur correction control, the blur correction lens may move during photographing, so that there is the possibility of the occurrence of finder image shake (blur) or the occurrence of deterioration in the photographed image. A mechanism for locking a blur correction lens is put forward in Japanese Patent Laid-open No. Hei. 9-80561.
An electromagnetic drive section having a magnet is employed in the related blur correction apparatus. Because high efficiency is required of this electromagnetic drive unit, the use of two expensive magnets is typical. This increases both the number of parts and the number of assembly steps.
In order to lock a blur correction lens, it is necessary to provide an electromagnetic drive section which may include a stepping motor or a latch solenoid (Japanese Patent Laid-open No. Hei. 9-80561), so that the blur correction unit becomes even larger.
Methods of mechanically locking blur correction lens in an interlocked manner with the turning off of a blur correction switch have also been put forward, but space is required for lock interlocking and the number of parts is increased.
It is therefore an object of the present invention to provide a small blur correction apparatus having a reduced number of parts.
It is a further object of the present invention to provide a blur correction apparatus having a locking mechanism that is highly reliable, difficult to operate in an erroneous manner, requires few parts and takes up little space.
In order to achieve the aforementioned object, a blur correction apparatus according to the present invention comprises a blur correction optical system acting to correct blurring and a blur correction drive section for electromagnetically driving the blur correction optical system. The blur correction drive section includes a permanent magnet, with one surface of the permanent magnet being used in the blur correction drive section and the other surface being used in another drive section for electromagnetic driving an object to be driven.
The blur correction drive section comprises a yoke fixed to the permanent magnet and having projections formed at prescribed intervals along the permanent magnet, and four coils provided opposite to both the permanent magnet and the projections with a prescribed gap and connected to the blur correction optical system.
The permanent magnet can be polarized into at least two poles within a plane. In this case, coils used in the other drive section for electromagnetic driving the object to be driven can be located in the vicinity of polarization points and it is preferable to support the blur correction optical system by four flexible wire-shaped members, at least two flexible wire-shaped members are provided in the vicinity of the points of polarization.
When a photographing optical system is equipped with the blur correction apparatus, the other drive section rotates about the optical axis of the photographing optical system.
The other drive section can be a lock drive section which limits movement of the blur correction optical system. The lock drive section comprises projections for fixing provided at a holding frame of the blur correction optical system, first and second rotating members for fixing which rotate about the optical axis having notches larger than the projections for fixing by at least a movable range of the blur correction optical system, and a rotation interlocking member which rotates the first and second rotating members for fixing in opposite directions. The projections are locked and unlocked as a result of the first and second rotating members for fixing which rotate in a relative manner so that respective notches shift relative to the direction of rotation.
A further blur correction apparatus of the present invention comprises a blur correction optical system acting to correct blurring; and a blur correction drive section for electromagnetically driving the blur correction optical system. The blur correction drive section includes a permanent magnet comprised of at least one of ring magnet and a plurality of arc magnets. The permanent magnet can be polarized into at least two poles within a plane. In this case, it is preferable to arrange coils used in the other drive section for electromagnetic driving an object to be driven in the vicinity of polarization points.
A further blur correction apparatus of the present invention comprises a blur correction optical system acting to correct blurring and a lock member limiting movement of the blur correction optical system. The lock member operates in a plane perpendicular to an optical axis of the blur correction optical system and in the direction of the optical axis. The lock member rotates about the optical axis of the blur correction optical system, and moves in the direction of the optical axis.
When a lock drive section driving the lock member and a lock urging member urging the lock member in the direction of the optical axis are also provided, the blur correction optical system can be locked and unlocked as a result of the lock member being driven by the lock drive section in the direction of the optical axis counter to the urging force of the lock urging member and the lock member being rotated about the optical axis by the lock drive section.
In this case, the lock drive section comprises an arc-shaped permanent magnet magnetically polarized into at least two poles within a plane and a lock coil positioned opposite the permanent magnet at a location in the vicinity of a position of changeover of the magnetic poles. The driving force in the direction of rotation with respect to the permanent magnet can then be generated when current flows in the lock coil and the direction of driving force in a direction of said optical axis is changed when a central position of the lock coil moves across the position of changeover of the magnetic poles.
The lock drive section can comprise projections for fixing provided at a holding frame of the blur correction optical system, first and second rotating members for fixing which rotate about the optical axis having notches larger than the projections for fixing by at least a movable range of the blur correction optical system, and a rotating, interlocking member for rotating the first and second rotating members for fixing in opposite directions. In this case, the lock coil is provided at least one of the first and second rotational members for fixing and the projections are locked and unlocked as a result of the first and second rotating members for fixing which rotate in a relative manner so that respective notches shift relative to the direction of rotation.
A further blur correction apparatus of the present invention comprises a blur correction optical system acting to correct blurring and a blur correction drive section for electromagnetically driving the blur correction optical system. The blur correction drive section includes four coils located evenly about the periphery of the blur correction optical system.